the functionality of music

Without a proper understanding of a music's purported function it's obviously very difficult to assess its success, let alone its value as good/bad, exciting/boring, etc. E.g. one might hear a typical comment concerning Gregorian chant (so-called) that it's 'boring'. One might respond 'duh'. Its entire function is to deliver liturgical text, and usually to do so in a way which elicits a prayerful attitude. If the same music were submitted to a club as a great dance mix then boring would be an appropriate assessment.

Determining what a music's function is is not always so easy. It's pretty much known by all that jazz or classical music during brunch or at a cocktail party is there to fill in the gaps in conversation, etc. [This is not a pejorative statement by any means. I play background guitar music from time to time (actually as often as I can!) and of course there are people there who do listen, but generally it's an easy gig from a pressure point of view. Also I was once in a bar in Opera City (in Shinjuku, Tokyo) at evening when a pianist came in and started playing Satie, etc. "Even" as background music it totally transformed the room...] But what is the same music's function when performed in a concert hall, or at a club where people are generally quiet and pay attention to the music? What was the function of a Pink Floyd concert?